Physiological And Biochemical Characteristics, Molecular Mechanism Of Self Incompatible Yali Pear And Its Self-compatible Mutations

Pear belongs to the kind of gametophytic self-incompatibility, so it is necessary to arrange varieties for pollination or perform artificial pollination for stable yield. Self-compatible cultivars have many advantages in pear production, so from 20 century 80th, it became the main task of fruit tree breeding of Japanese, and had selected one self-compatible cultivar Osa- Nijisseiki(genotype S₂S₄SM) from Nijisseiki i(genotype S2S4), and studied it thoroughly. Yali pear is the representative of Pyrus bretschneideri Rehd. of China, and two self-compatible cultivars that Jinzhuili pear and Weixianyanzhuangzihuajieshiyali pear were selected from Yali pear, but their self-compatible mechanisms were unknown, this restricted the researches of self-incompatibility of Chinese pear and breeding self-compatible cultivars, so it is necessary to study the mechanism of self-compatible.In this thesis self-incompatible strength, physiological and biochemical characteristics related to self-incompatibility, molecular mechanism of self-compatible and adjustment methods of self incompatibility of Yali were studied. The results were as follows.1. Self incompatible strength of 17 pear cultivars were identified by self pollination tests and observation of the amount of pollen tubes from style bottoms and percentage of style with pollen tubes through their bottoms in semi vitro culture of self pollination styles. Weak SI cultivars were Jinzhui pear, Weixianyanzhuangzihuahieshiyali pear, Atago, Lvbaoshi and Shinsetsu; intermediate SI cultivars were Kisui, Bayuehong, Qinfeng and Nijisseiki; strong SI cultivars were Kohsui, Housui, Shinko, Beurre Bosc, Yali pear, Whangkeumbae, Pakeshengli and Xuehuali pear.2. Physiological and biochemical characteristics aspects, there exited very significance negative correlation between POD and self pollination fruit set percentage, the correlation coefficients among POD and fruit set percentage of inflorescence and fruit set percentage of flower were -0.935and -0.888; their hadn't significance correlations among SOD, CAT, MDA and fruit set percentage. SOD, POD, CAT activities and MDA content changes in styles of Yali pear and Xuehuali pear after self- and cross-pollination weresingle apex curves, SOD, POD, MDA reached the peak after pollination in 24h, and CAT activity reached the peak after pollination in 48h. At the same time after pollination, SOD, CAT activities in styles by cross-pollination were higher than self-pollination, but POD activity and MDA content in styles by cross-pollination were lower than self-pollination.3. About hormone and self-incompatibility, endogenous hormones contents of IAA, GA3, ZR that promoted growth in styles before pollination of Jinzhui pear were significantly higher than that in Yali pear. ABA content was significantly lower than that in Yali pear.In the period of 72h after self-pollination, IAA, ZR contents in styles of the two cultivars tended to decline. During 24h after pollination, GA3 contents in styles declined, then rose. ABA content in styles of Jinzhui pear rose at 24h after pollinated, and then declined. During 24h after pollination, ABA content in styles of Yali pear tended to decline, then rose. Changes of endogenous hormones contents in Yali pear styles after cross-pollination were dissimilar from self-pollination, the contents of IAA, GA3, ZR in styles approached the contents of Jinzhui pear after self-pollination. Changes of IAA oxidase activities in styles of the two cultivars after self and cross-pollination opposed to that of IAA contents; at the same time, IAA oxidase activities after self-pollination of Yali pear were lower than that of cross-pollination; IAA oxidase activities in Jnzhuili pear styles after self-pollination were always lower than that of Yali pear, and 24h after self-pollination, it approached the activity of Jinzhui pear after self-pollination.4. There exited inhibition of style extract on pear pollen germination and pollen tube growth, and with the style extract concentration raising, the pollen germination percentage declining, inhibition degree of pollen germination and pollen tube growth raising. The inhibition degree of Yali pear style extract to pear pollen germination and pollen tube growth of Yali pear and Weixianyanzhuangzihuahieshiyali pear was higher than that of Jinzhui pear. The inhibition of Jinzhui pear style extract to Weixianyanzhuangzihuahieshiyali pear was higher than that of Jinzhui pear and Yali pear. The inhibition of Weixianyanzhuangzihuahieshiyali pear style extract to Yali pear and Jinzhuili pear was higher than that of Weixianyanzhuangzihuahieshiyali pear.5. Physiological and biochemical characteristics related to self-incompatibility of Yali pear were as follows. IOD and POD activities which has IOD activity in styles before pollination were higher, endogenous hormones contents of IAA, GA3, ZR that promoted growth were lower, but ABA content was higher; the inhibitions of self-incompatible style extract on its pollen germination and pollen tube growth were strong; but the changes of styles endogenous hormones contents and protected enzymes of self-compatible cultivars after self pollination were similar to that of Yali pear after cross compatible pollination, and the inhibitions of self-compatible style extract on its pollen germination and pollen tube growth were weak.6. S gene PCR amplification of Yali pear and its self-compatible mutations that wereWeixianyanzhuangzihuajieshiyali pear and Jinzhuili pear were detected by 8% PAGE, the results showed that there were two binds at about 370bp of Yali pear and Jinzhuili pear, but there was only one bind of Weixianyanzhuangzihuajieshiyali pear, indicated that there was one S gene mutated of Weixianyanzhuangzihuajieshiyali pear, then resulted in self-compatible; more analysis indicated that Yali pear contained SI gene, and SI gene of Weixianyanzhuangzihuajieshiyali pear was normal, its self-compatible molecular mechanism was another S gene mutated. The self-compatible molecular mechanism of Jinzhuili pear might be the modifying gene controlled S gene expression mutated.7. Effects of polyamine on pollen germination and pollen tube growth of Yali pear varied from the concentration of polyamine, the concentrations of spermine that promoted pollen germination and pollen tube growth of Yali pear were 0.005-0.01 mM; that the concentrations of spermidine that promoted pollen germination of Yali pear were 0.01-0.25 mM, at the tested range of spermidine concentrations, pollen tube length of Yali pear was longer than that of control significantly or very significantly; the concentrations of putrescine that promoted pollen germination and pollen tube growth of Yali pear were 0.01-0.5 mM. When the concentration of MGBG was in 0.05 mM, it promoted pollen germination of Yali pear, and other concentrations inhibited pollen germination; when the concentrations of MGBG below 0.25mM, it promoted pollen tube growth of Yali pear very significantly, when it exceeded 0.25mM, it inhibited pollen tube growth of Yali pear.8. Sprayed polyamine in a concentrations range of polyamine enhanced self pollination fruit set of Yali pear very significantly. Semi vitro culture of pollinated styles indicated that there exited very significance of the amount of pollen tubes from style bottoms and percentage of style with pollen tubes through their bottoms by different concentrations of polyamine, the numbers of pollen tubes from style bottoms and percentages of style with pollen tubes through their bottoms treated by 0.0 lmM Spm, 0.05mM Spd and Put were the best. The result showed that polyamine could break self-incompatibility of Yali pear at some extent.9. In a concentrations range of salicylic acid promoted pollen germination and pollen tubes growth, in the range of tested salicylic acid concentrations, percentages of pollen germination of Yali pear were higher than control significantly or very significantly, the best was 0.005 mM, with the concentrations raising, percentages of pollen germination declined rapidly; the suitable SA concentration that promoted pollen tubes growth was 0.005mM, when exceeded this concentration, the promotion effect of SA on pollen tube growth was weakened sharply. Sprayed 0.005-0.025 mM SA, there had lower fruit set percentage of inflorescence and fruit set percentage of flower; the number of pollen tubes from style bottoms and percentage of style with pollen tubes through their bottoms treated by 0.005mM SA was the best. But the fruit set was very low, and couldn't fill the yield, so considered that SA couldn't break self-incompatibility of Yali pear.10. There exited very significance differences of the number of pollen tubes from...